The photoluminescence of SrAl2O4:Sm phosphors

A red emitting SrAl2O4:Sm phosphor powder was synthesized by the solid-state method. The phosphor showed Sm3+ emission when fired in a reducing atmosphere at 1200 °C. The intraion emission spectra of Sm3+ (image) indicates image reaction to occur with intense emission lines located at 562, 596 and 643 nm. Results indicate that fluxing agents such as LiF and B2O3 play an important role in the photoluminescence (PL) emission intensity of SrAl2O4 powders. Also an increased content of the hexagonal phase in the SrAl2O4 powder boosts the PL intensity. The emission intensity becomes stronger as the firing temperature increases from 600 to 1200 °C. SrAl2O4:Sm shows the maximum PL intensity at 10 wt% of B2O3 addition. The B2O3 addition affects the spacing of the (image) planes but not the (2 2 0) and (2 1 1) planes. This derives from B3+ ion replacing the Al3+ ion in the (image) plane and causing shrinkage of the crystal lattice, which induces crystal defects and hence produces a stronger PL intensity.